Power hammer



United Sttes Patent POWER HAMMER Howard F. Caudill, Lutz, Fla., assignor to C. L. Guild This invention relates broadly to power hammers and more particularly to that general category of hammers which operate by means of uid pressure such as steam or compressed air. Within this general category of power hammers, there are two distinct types. The first type is what is known as a single-acting hammer, which utilizes the motive uid on the upstroke of the piston to raise the ram and thereafter exhausts the motive fluid to permit the piston and the ram to fall by gravity and strike a blow due to the acceleration of gravity alone acting upon the ram. Such a hammer has a measured stroke or free fall of a known weight, whereby the driving energ'y can be accurately determined, inasmuch as slight variations of the motive uid pressure do not affect the power of the blow. The second type of hammer, known as a double-acting hammer, not only utilizes the pressure of the motive fluid against the piston to raise the ram, but also uses this pressure to accelerate the ram on the down stroke. In this type of hammer a relatively light weight ram coupled with a relatively short stroke will develop about three to four times the driving energy of a similarly sized single-acting hammer. However, this type of hammer has the disadvantage of depending upon the pressure of the motive fluid and therefore the driving power of such a hammer may not necessarily be constant. Accordingly, a double-acting hammer is not t be preferred where exact driving energy is desired. It is apparent, therefore, that a hammer selection must be made for each type of job.

This invention is designed with a View of obviating the necessity of using two distinct types of hammers and is characterized by providing a power hammer with optional operation; that is, the hammer may operate as a single-acting hammer where exact driving energy is required as in driving foundation piling to a known bearing capacity or as a double-acting hammer where increased driving power is advantageous in driving such items as steel sheet piling and the like.

-It is therefore the principal object of this invention to provide a construction of a power hammer which may be readily changed so as to operate either as a single-acting hammer or as a double-acting hammer.

Another object of the invention is to provide a simple means for controlling the distribution of the motive uid into the piston cavity.

A further object of the invention is the provision of a power hammer which may be alternately operated either as a singleor `a double-acting hammer and in which the parts comprising the changeover assembly are held at a minimum.

With these and other objects in view, the invention consists of certain novel features of construction as will be more fully described and particularly pointed out in the appended claims.

In the drawings:

Figure l is a vertical sectional View taken substantially centrally through the hammer which is constructed in accordance with the invention;

'2,969,771 Patented Jan. 31, 1961 Figure 2 is a sectional view taken substantially on lines 2-2 of Fig. 1 showing the arrangement of the valve intake and exit ports; and

Figure 3 is a vertical sectional view ion an enlarged scale showing the valve block assembly and taken sub- ,stantially on lines 3--3 of Fig. 2.

Referring now to the drawings for a more detailed description of the various parts of the device, there is shown in Fig. 1 a power hammer having a suitable housing which is in the form of an upper cylinder 11 and a lower cylinder 12. Between the two cylinders 11 and 12 is a valve block 13 and at the upper end of cylinder 11 is a cylinder head assembly 14, while at the lower end of cylinder 12 is a retaining ring 15. These two cylinders and the valve assembly are held together in operative arrangement between the head 14 and the ring 15 by a plurality of tie rods 16 which tie rods are provided with suitable threaded ends and nuts as at 17. Disposed within the upper cylinder 11 is a piston 18 which piston is provided with one or more piston rings 19 suitably disposed within grooves in a manner known to those mechanics skilled in the art. Attached to and extending from the piston 18 is a piston rod 20 that passes through a bore 21 in the valve block 13 and has threadingly attached at its lower end a ram 22. Disposed in suitable grooves in the periphery of the ram 22 are one or more piston rings 23 which provide sea-ling engagement with the interior bore of the'lower cylinder 12. Located at the lower end of the cylinder 12 is an anvil block 24 which has a reduced diameter section as at 25 which is received within the retaining ring 15.

Motive fluid for operating the power hammer may be supplied by means of an inlet pipe connection 26 which is located on a boss 27 forming a part of the valve block 13. This connection 26 communicates with a horizontal passage 28 and a vertical passage 29. Passage 28 communicates with an upper valve chamber 30 while the passage 29 communicates with a lower valve chamber 31. Disposed within each o-f the valve chambers 30 and 31 are valve plugs 32 and 33 respectively, which plugs are generally cylindrical to t within the generally cylindrical chambers 30 and 31 and are provided with a plurality of axial bores 34 and 35 respectively. The two valve plugs 32 and 33 are joined together for simultaneous action by a valve stem 36 which stem extends outwardly of the valve chambers 30 and 31 a substantial distance for a purpose which will presently appear. The valve chambers 30 and 31 open into the upper and lower cylinders 11 and 12 respectively and have communicating therewith exhaust ports 37, 38 respectively. Disposed at the lower end of the vertical passageway 29 is a control valve cock 40 which is provided with `a stem 41 that is adapted to rotate in a suitable packing means 42, rotating being imparted by virtue of the nut 43 at the end of the stem 41. In the position shown in the drawings, this cock is shown as closing o an outlet port 44 so that thru communication is had'from the passageway 29 through port 29A into the valve chamber 31.

As viewed in the drawings, in Fig. l the hammer is midway of its stroke, while in Fig. 3 the hammer is at the end of i-ts downward stroke at which location the bottom face of the piston 18 is in contact with the upper end of valve stem 36. This causes the valve assembly consisting of the stem and two valve plugs 32 and 33 to be pushed downwardly to a point where the inlet pipe connection 26 is in communication with the upper cylinder 11 through passageway 28. Additionally, the exhaust port 37 is closed, the intake port 29A is closed, and the exhaust port 38 is open leaving communication from the lower cylinder to the exhaust port 38 through the ybores 35 of the valve plug 33. Accordingly, as the pressure from the motive uid enters the upper cylinder 11 below the valve plugs upwardlyras ,viewed inthe A,drawing ftpa point where the intake passageway 2R81 iselosedathe .exhwusr part .311s ensued-incinta@ .PartlefiS-.spsned and the .exhaust 'pews-fis .clases-- The fssvrefrm the motive fluid then entersqthe lower der 12 .nforcing thefram downwardly tothe end of .itsmstrokefwhere it strikes theganvilblock 24.and,c l elivers.its driving energy to the object beisssrivsn- Trhisthen .cgmplss .0116

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scribed except -that when the piston 18 reachesthe ltop' of its stroke and the ram 22 pushes the valve rod 36 upwardly thereby closing off communication between the upper cylinder 11 and the passageway28, the lower cylin der will then be opened to theatmosphere via exhaust port 44 and allow the lower cylinder to take in airron the downward stroke, Ythus avoiding atendency to form `a vacuumA in the Alower cylinderQ-.IZ .as vthe .ram v22.

descends.

It .will be apparent `that thereais disclosed apower hammer which may readily be operated.. either` as. a singles acting or a `double-acting device merely, by a simple rotation .of .a valve cock.. Theentire .valve assemblyvis extremely `simple in construction and whiiein the foregoing description there has 4beeneliminated many' details of actual construction of theentire device, it sutlices to say that suitable means are .provided through the bore 21 of the valve body` 13 to prevent leakage of motive tluid pressure from the upper cylinder to the lower cylinder or vice versa. Further, it should beappreciated that the valve plugs 32 .and 33 are in a. closesliding twith the walls of the valvechambers 30and 31 and of course` if preferred, suitable sealing means between-the valve plug and the `valve chamber walls may beprovided.. Nol

particular packing vis .necessary y.around the valve stem 36 between the chambersland 3 1 for yany leakage therebetween isnot detrimental to the operation ofthe device.

It should beparticularly'noted in connectionwith ,the

valveassembly that .no means Aare shown tov maintain the valve plugs in theindriven position. This is due to the fact that the pressure of the motive uid arriving through theappropriate intake port issuficient to. maintain the valve plugs in position. during ythe necessaryvtravel of the piston 18 between its lextreme positions. If, of

course, under certain conditions such an arrangement Idoes not provev feasible such as extremely' adverse -operating conditions, then suitable means well known to those skilled in the art can be utilized to provide a positive stop for the valve plugs at each end of their travel, which stop means will retain the valve plugs in the desired position.

It should be pointed out further that the power hammer disclosed is capable of working as a single-acting hammeratwany angular orientation sufficiently above a horizontal so thatflthe ram will fall under the influence of gravity, and of course, will workV as a double-acting hammer infanyv position. Further, such `a hammer is capable of operating under water, it merely `being necessary to modify the lower end of the hammer at the anvil portion to prevent water entering at this particular location surrounding the anvil block.

I claim:

1. In a pile driving. hammer having an upper cylinder.

and a lower cylinder, a valve block disposed between said cylinders and a piston disposed in said upper cylinder with a piston rod connected .thereto and passingrthrough saidvalve block into said lower `cylinder and attached to a ram valve means for supplying motive fluid comprising two valve chambers Vlocatedwithin said valve block, one of said chambers communicating with said upper cylinder, the other of said chambers communicating with said lowercylinder, valveplug means disposed withinr each valve cham-ber, apair of passageways for supplying motive uid to eachvalve chamber, means located within one of said. passageways to close oi said passageway and simultaneously vent the associated valve chamber whereby :by the operation of said last 4named means .the hammer maybe changed from a doublefacting hammer to a singleacting hammer.

2.. In a hammer as in `claim 1 wherein exhaust ports are disposed within each of said valve chambers and said valve plugs have a plurality of `passageways therethrough, means for operating said valve pl'ugs in unison so that when onevalve chamber is closed, the other valve chamber will be opened.

3. In a. hammer asinclaim l wherein the said one passageway has an exhaust port andthe means located within the one of said passageways normally closes the exhaust port within vsaid passageway and upon operation.

closes oi said passageway Opening the valve chamber in communication `therewith to said exhaust port.

References Cited in the tile of` this'patent UNITED STATES PATENTS Kupka et al Apr. 23, 1957 

